Cooled nozzle construction



June 15, 1965 J. c. PROSSER 3,183,801

COOLED NOZZLE CONSTRUCTION Filed Sept. 29', 1961 V INVENTOR. (/5! (272%): 920;: BY

ATTORN Y tially surround the throat United States Patent This invention relates to a reaction mot-or exhaust nozzle construction, and more particularly to a cooled nozzle construction. In general, it consists of an assembly of porous members cooled by the effusion of a coolant through the porous walls.

The extremely high operating temperatures of modern day reaction motor exhaust nozzles, such as are used in connection with rockets or the like, require that a cooling system be provided for the nozzle so that the material of which the nozzle is constructed will be maintained at a temperature below its melting point. Otherwise, the nozzle lining will burn out during initial engine operation resulting in a failure of the engine.

Therefore, this invention relates to a nozzle constructed to be cooled by the effusion of a coolant through porous members forming the nozzle.

It is therefore an object of this invention to construct a nozzle of porous members contacted by a coolant for the effusion of the coolant through the porous members.

It is a further object of this invention to circumferensection of a porous convergentdivergent type nozzle with cooling medium manifolds to cool'the higher temperature portions of the nozzle by the effusion of the coolant through the porous material.

Other objects, advantages and features of the invention will become apparent upon reference to the succeeding detailed description of the invention, and to the drawings illustrating the preferred embodiments thereof, wherein:

FIGURE 1 is a side elevational view with parts broken away and in section of a nozzle embodying the invention;

FIGURE 2 is an enlarged view of a detail of FIGURE 1;

FIGURE 3 is an enlarged cross sectional view taken on a plane indicated by and viewed in the direction of the arrows 3-3 of FIGURE 2;

FIGURE 4 is a perspective View of a portion of the FIGURE 2 showing, and;

FIGURE 5 is a view corresponding to FIGURE 2 showing a modification of the invention.

in general, the invention relates to constructing a cooled convergent-divergent jet exhaust nozzle by fabricating a number of longitudinally extending channel-shaped members from a porous material, circumferentially juxtaposing the members to form the nozzle, and surrounding the throat section of the nozzle with a cooling medium manifold so that the throat will be cooled by the effusion of the coolant through the porous walls of the members onto the surface of the nozzle throat.

More specifically, FIGURE 1 illustrates the invention schematically in connection with a nozzle of the convergent-divergent type, although it will be clear that th invention would have uses in many other installations than that shown wherein it is desired to cool a high temperature area. Nozzle 10 has a diverging nozzle exit portion 12, a throat portion 14 of minimum cross sectional area, and

" a converging nozzle portion 16. Portion 16 is, in this installation, formed integrally with the aft end of a rocket casing 18, although it will be clear that it could be suitably connected to it by other means, such as bolted flanges, for example.

As'best seen in FIGURES 2, 3 and 4, the nozzle it consists of an assembly of thin longitudinally extending members 20 each continuous throughout its length and fabricated from a material having a high degree of porosity. The members each have a channel-shape in cross section and are contoured longitudinally to the desired convergent-divergent shape as shown. Thus, each channel has the shape of an angular segment of the nozzle. The individual porous segments 2% are assembled together to form the circular nozzle shape by being circumferentially arranged and juxtaposed with the open portion 22 of each of the channels facing radially outwardly. The abutting sides 24 of the segments are joined at their outermost radial edges 26 by fusion welding, for example, so as to maintain or preserve the porosity of the segments 20 on their radially inner surface 28. Thus, an annular gas exhaust duct 36 is formed having a substantially continuous smooth and streamlined porous wall 32 defined by the juxtaposed inner surfaces 23 of the porous segments 20.

The pressure and temperature of the exhaust fluid as it passes through a convergenbdivergent nozzle normally increases progressively to a maximum at the throat, and then decreases progressively upon expansion of the gases through the bell-shaped outlet. With the use of modern day fuels, the temperature of the exhaust gases at the throat portion may reach 6500" E, for example, which is several hundred degrees above the melting point of known materials for lining the throat. Also, the gas pressure at the throat is exceedingly high, say 506 p.s.i., for example. Therefore, the throat should be cooled by a coolant of high specific heat capacity flowing at a pressure slightly greater than the pressure of the exhaust fluid in the throat.

To meet the varying pressure requirements at different points along the throat, a number of axially separated individual cooling manifolds rather than one are used to cool the throat. More specifically, as best seen in FIGURES 1 and 2, the axial length of the throat section is surrounded by six individual annular coolant manifolds 34. Each manifold has a hat-shape in cross section with its edge flanges as form-ed with a V-shaped groove 38. As seen more clearly in FIGURE 4, each of the sides 24 of the porous nozzle segments 26 has a number of axially spaced V-shaped notches 4% along the throat section to accommodate the V-shaped flanges of each of the cooling manifolds. Each of the manifolds consists of two half rings fusion welded or otherwise joined together after being fitted to the nozzle. Each of the half rings is assembled to the nozzle by fitting its flanges 36 in the notches 4t) of segments 20. A retaining wire 42 is then wound in the groove of the VS around the joined half rings to maintain the manifolds in place and prevent the leakage of coolant past the apex of the VS into the longitudinal troughs formed by the open portions 22 of the segments 2!). Brazing foil is deposited under each V flange so as required. This construction assures that the cooling medium will flow by effusion through the porous walls 28 of the nozzle segments as only at the throat section. Each of the manifolds 34 is constructed substantially alike, the slight differences in shapes and sizes being only to contain the proper proportion of coolant at a particular pressure and direct it through a particular portion of the throat.

The means for supplying coolant individually to each of the manifolds and the details of the inlets to the manifolds are shown schematically since they may be of several types and their details are not essential for an understanding of the invention. Suffice it to say, however, that for reasons apparent, each of the cooling manifolds is adapted to be supplied with a suitable liquid coolant 46, such as water or the like. The water in each manifold is at a pressure different from the others and slightly higher than the existing pressure of the exhaust gases in the region 48 of the nozzle throat opposite the particular manifold. Manifold 49 will therefore have water at the highest pressure, with the manifolds on either side containing water at lower pressures. A pressure differential theredifferent pressures, or restrictive conduits of'difierent 1 sizes. .Such a coolant supplying system is shown in FIGURE 1. Each manifold34 is supplied with coolant througha conduit 35 containing an orifice or restriction 37. The 'flow of coolant through these conduits 35is received from a pressurized coolant source 39 through "pump' 43 and controlled by a pressure regulator valve 41.

=After the cooling manifolds" have been secured to the outside of the nozzle in the maner described, the entire -noz'zzle assembly'is then preferably Wrapped with wire or' tape 50 and brazed into an integral assembly. The *wire or tape Wrapping provides additional strength'for the porous material and provides the hoop strength required for the nozzle. 7 V i p In operation, the rocket exhaust gases pass axially from right to-left as seen in FIGURE 1' 'throughthe converging section 16*and the throat 14. Simultaneously, 'water at' the proper pressure in each ofthe manifolds 34 flows through-the porous Walls 28 of the segments 20 between the 'V-shaped notches 40 onto the inner'su'rfa'ces' 32 of the nozzle throat surface, 'and is vaporized to cool this-surface. The vaporized coolant then passes downstream of the nozzle with the exhaust gases. 7 V

. While the cooling'm'anifolds are shown surrounding only the throat 'section of thenozzle, it will'be clear that additional manifolds would be providedaround the convergent and/or divergent nozzle portions to cool these sections of the nozzle if it is deemed necessary. However, since the exhaust gases flowing through these sections are generally lower in temperature than the melting V temperature'of the materials of which these nozzle sections'are construc'ted or fabricated, the cooling or" these portions is generally'unnecessary. V

7 FIGURE 5 shows a' modification of the invention using a solid" coolant instead of the liquid illustrated for-use in the embodiment of FIGURES 1 through 4. In FIGURE 5, the construction of 'the'manifolds' 34 and the manner in'which they are. secured to the nozzle segments"20 is substantially the same as in FIGURES 1 through 4. The details,"therefore, will not be repeated. The only differences between the constructions are that the'manifolds difiicult to form, and the coolant manifolds provide additional strength for the. porous-nozzle material. Also, the method of; joining the channels at their outermost radial edges preserves the basic porosity of the material on the inner surface,'i.e.', the wallin contact with the exhaust gases. Furthermore, the construction described assures that all-jointsare on the cool side of the coolant Wall enabling full realization of base material properties even though the joint materialhas a lower -meltingtemperature.

Still further, the small coolant passages inherent in the design reduce 'the material thickness-necessary for Withstanding the pressure loads. And finally, the invention *permits the :constructionof: thelightest possible cooled nozzle due tothe use of thin materials and 'the maximum storage of coolantwin the structure proper.

' While the invention has been illustrated in itspreferred embodiments in the figures, it will beclear to those skilled in the arts toiwhich this inventionpertains"that'manymodifications and changes may bemade thereto'mwithout departingfrom the scope of theinvention.

What'is claimed-is: 1. A 'cooledrea'ction rnotorexhaust duct comprising: a plurality of adjacent porous channel members extendinglongitudinally of said duct, said porous' members being attached to 'each other to define a convergent-divergent'fiow passage with a throat portion of minimum'area; y and a plurality of axially aligned "coolant manifolds circumferentiallysurroundingsaid exhaust duct and containing a coolant substance under'prcssure,=said coolant manifolds being located adjacent to the radially outer po'rtions'of .said porousmembers'for the 'efiusion of said'coolant substance radially inwardly through said porous membersonto the inner surface of said porous members to cool said inner surface and saidexhaust duct. formed thereby, said coolant substance beingvaporized. by the heat from the exhaust "fluid as' it passes through said fl'ow passage so that-the pressure of said coolant-substance be- 'comes greaterthan that of said exhaustfiuid thereby inducing said coolant substance to flow through said porous members to 'cool said i exhaust duct, the pressures 1 ineach individual coolant: .manifold 1. be- 'ing diiferent *from the other coolantmanifolds. i-"A cooled reaction-motorexhaust duct as described in claim 1 wherein said coolantsubstance is illiquid-supplied under-pressure by a pressu'rizingsource-so-that it 34' areincreased in size and shape .slightly as compared to those of FIGURE 2 to accommodate blocks of a coolant "54in its solid state, such as nylon, for. example. Nylon 'is an excellent coolant since it is' relatively unstable as a liquid and changes from its solid' state substantially directly intoits vaporstateat a temperature'well below thenormal'operatingtemperature'of' th'e'exhaust gases ,passing through the throat section of the nozzle. Since themanifolds are enclosed andse'aled at their outer diameter, the'fn'ylorr expands upon change to'itsi gaseous state crea'tihgia highpre'ssure forcing the coolant out fthroughthe'walls' '28 ofthe porous segments 20. "Therefore, vaporizationi of the. cooler. nylon causes it" to' fl'ow by'fi1isiofi throu'gli'the' porous nozzlese'grrients '20 onto the throat surface 32, to maintain thethroat cooled. Iri'all' other respects; the FIGURE .5 modification oper- "ates in the same manner as'thatof FIGURES lthrough't. From theforegoing',therefore, it will. be seen that the fiiiverltion' provides a cool nozzle construction with accurate 1 control lot the. coolingv by a system of controlled pressurization of each nozzle coolant manifoldinsuring proper 'jfiow of coolant through the porous nozzle wall. The channel section type of construction provideshigh strength nozzle members frornmaterial that is basically weak and efiuses through said porous membersdo coolsaid exhaust duct. 50

- in claim l-wherein s'aidcoolant substance is a solid held "within said coolant manifolds 'and vaporized therefrom through saidporous members tocool said exhaust-duct.

3. A cooled reaction mOtOreXhaust duct as described 1 4.'-A cooled reactionmotor exhaust duct com-prising: a: plurality-of; adjacentporous channel members extending longitudinally of saiclduct, said porous members being-attached t'o each' otherto define-a convergent-di-vergent fiowpassage with a throat portion of minimum area; e a plurality of axially aligned Coolant -manifolds=cir- V -cumferentially'surrounding said exhaust duct and containing a cool-ant substance under pressure, said i coolant manifolds. being located adjacent to the radial-ly outer-portions -ot saidf porous members so that the I coolant substance {is vaporized and efiused from'said coolant manifolds through said porous membe'rs onto the inner surface of said porous members to cool the inner surfaceand-the exhaust duct formedthereby; 1 and means maintainingisaid coolant substance attdiverse levels of pressure in said coolantmanifolds so that the pressure of said coolant substancebecomes greater than that of said exhaust fluid=thereby:induc -1ng said coolant substance-to flow I through said porous members to cool said exhaust duct.

5. A cooled reaction mot-or exhaust duct as described in claim 4 wherein said coolant substance is a liquid supplied to said coolant manifolds at diverse pressures by a pressurizing source so that it effuses through said porous members to cool said exhaust duct.

6. A cooled reaction motor exhaust duct as described in claim 4 wherein said coolant substance is a solid sealed Within said coolant manifolds and vaporized therefrom through said porous members to cool said exhaust duct at diverse pressures due to the varying temperature of the exhaust flow pressure through said exhaust duct.

References fitted by the Examiner UNITED STATES PATENTS Africano et a1. 6035.6 Baehr 6039.66X Kunz 60-356 X VOnder Esch 6035.6 Scully et a1.

Runton et al. 10292.5

10 SAMUEL LEVINE, Primary Examiner.

JULIUS E. WEST, ABRAM BLUM, Examiners. 

1. A COOLED REACTION MOTOR EXHAUST DUCT COMPRISING: A PLURALITY OF ADJACENT POROUS CHANNEL MEMBERS EXTENDING LONGITUDINALLY OF SAID DUCT, SAID POROUS MEMBERS BEING ATTACHED TO EACH OTHER TO DEFINE A CONVERGENT-DIVERGENT FLOW PASSAGE WITH A THROAT PORTION OF MINIMUM AREA; AND A PLURALITY OF AXIALLY ALIGNED COOLANT MANIFOLDS CIRCUMFERENTIALLY SURROUNDING SAID EXHAUST DUCT AND CONTAINING A COOLANT SUBSTANCE UNDER PRESSURE, SAID COOLANT MANIFOLDS BEING LOCATED ADJACENT TO THE RADIALLY OUTER PORTIONS OF SAID POROUS MEMBERS FOR THE EFFUSION OF SAID COOLANT SUBSTANCE RADIALLY INWARDLY THROUGH SAID POROUS MEMBERS ONTO THE INNER SURFACE OF SAID POROUS MEMBERS TO COOL SAID INNER SURFACE AND SAID EXHAUST DUCT FORMED THEREBY, SAID COOLANT SUBSTANCE BEING VAPORIZED BY THE HEAT FROM THE EXHAUST FLUID AS IT PASSES THROUGH SAID FLOW PASSAGE SO THAT THE PRESSURE OF SAID COOLANT SUBSTANCE BECOMES GREATER THAN THAT OF SAID EXHAUST FLUID THEREBY INDUCING SAID COOLANT SUBSTANCE TO FLOW THROUGH SAID POROUS MEMBERS TO COOL SAID EXHAUST DUCT, THE PRESSURES IN EACH INDIVIDUAL COOLANT MANIFOLD BEING DIFFERENT FROM THE OTHER COOLANT MANIFOLDS. 